The utility distribution line and associated valve are normally installed in an excavated trench. With the valve box placed over the valve, the excavated trench is then backfilled and graded. It is during this backfilling and grading operation that the valve box is often knocked out of proper alignment with the valve making it difficult, if not impossible, to gain access to the valve from the upper ground surface. In some cases the valve box must be excavated to regain access to the valve. This procedure is expensive and in some cases may present a danger to the public if immediate access to the shut-off valve is critical. In an effort to resist the lateral forces placed on the valve box during the backfilling procedure several arrangements have been devised to support the valve box and to center its position relative to the valve. Examples of such prior art devices are shown in U.S. Pat. Nos. 3,548,864, 4,534,378 and 4,556,081.
In U.S. Pat. No. 4,534,378 the bottom portion of the valve box is received within U-shaped arms extending from a ring mounted on the valve housing. The U-shaped rings provide vertical support and center the valve box on the valve housing. However, during a backfilling operation, the valve box can be knocked off the U-shaped arms since the arms provide only minimal resistance to lateral forces acting upon the valve box.
U.S. Pat. No. 4,556,081 provides another support structure in which vertical guides position the valve box in relation to the valve. However, once again these guides are inadequate in preventing the valve box from being displaced or misaligned.
U.S. Pat. No. 3,548,864 provides a centering means in the form of a conduit guide through the body of the valve box. If, however, lateral force is applied against the valve box it will rotate about the conduit and tip in relation to the valve housing.
Other prior art arrangements have suggested apparatus for attaching the valve box to the valve housing. For example, U.S. Pat. No. 996,956 suggests a clamp arrangement that attaches to the valve housing and extends vertically into the body of the valve box. The clamp provides only a minimum contact area with the interior of the valve box housing. This minimum contact area can act as a pivot point allowing the valve box to tilt in relation to the clamp in the valve.
U.S. Pat. No. 4,030,519 suggests the use of plastic resilient fingers extending from the valve box and clamping on the conduit leading into the valve. With this arrangement the valve box can rotate about the conduit and thus be vertically misaligned with the valve housing.
U.S. Pat. No. 4,308,886 suggests a valve box arrangement with valve engaging projections which are forced into frictional engagement with the valve side when the valve box is placed on the valve. The frictional engagement of the projections provides insufficient resistance to the lateral forces experienced by the valve box during the backfilling operation. Further, such an arrangement requires that the valve box be specially constructed for each type of valve encountered in order that the projections encounter and frictionally engage the valve housing.